Menu Driven Program in C

Introduction to Menu Driven Program in C

It is always easier to choose something from a handful of options rather than picking something from an ocean of choices. Also, it is much easier to choose something from a collection if the collection is very well organized. This is where menus come into the picture. A menu is simply a list of items that can be used to provide an overview of something. For example, in a restaurant, a menu is used to provide an overview of the dishes that the restaurant offers. This article also contains a menu using which you can navigate and access different sections of the article. Now, how do we apply this concept of menus in software development? This is where menu-driven programs are used!!!

A menu-driven program is simply a program that provides a collection of options to the user. Based on the choice of the user, a specific set of statements is executed to provide a good user experience. Systems using menu-driven programs have limited choices and are more user-centric than other kinds of programs. Because of the limited and specified type of choices, these systems are less prone to user errors and are more user-friendly than command-line interfaces.

Algorithm for Menu Driven Program in C

Menu-driven programs are choice-based programs that are used to execute a set of statements based on the user's choices. The general algorithm for the menu-driven program in C is:

• Step 1: START
• Step 2: Take the choice input from the user.
• Step 3: Execute a specific set of statements according to the user's choice.
• Step 4: Repeat Step 3, till the user selects a valid option in Step 2.
• Step 5: STOP

Now, let's look at implementing the above algorithm in the C programming language.

Examples of Menu-Driven Programs in C

We can create a menu-driven program in C using simple if-else ladders. Let's look at an example to understand this concept:

Code:

Output:

In the above example, we are using the while(1) statement to create a loop for infinite iterations. The user can choose any option (Coffee, Tea, or Exit) from the menu by providing a numeric input which is stored in the choice variable. According to the user's choice, a specific block of code is executed from the if-else ladder. The user can exit from the loop by selecting the 3. Exit option. This option makes use of the break keyword to terminate the execution of the loop.

Program to Create a Menu Driven Software in C

Now, let's consider a real-world example and try to develop a menu-driven calculator using the C programming language. Similar to the previous example, we will use the if-else ladder to define various functionalities. Let's look at the source code for our calculator:

Code:

Output:

In the above example, we are using the if-else ladder to provide the arithmetic operations feature to the user according to his/her choice.

Now, let's look at a new way using which we can implement menu-driven programs in C.

Program to Create a Menu Driven Software in C Using Switch Case

Apart from using the if-else ladder, we can also use the switch statements to implement a menu-driven program in C. A switch statement is a special statement that allows us to execute specified blocks of code depending upon the value of a variable known as the switch variable. Let's look at an example to understand the implementation of the menu-driven program using the switch statement:

Code:

Output:

In the above example, we are using a flag variable as a condition for the while loop. This flag variable is used to terminate the execution of the loop when the user selects the Exit option. Also, we are using the switch statements to define the specific functionality which will be executed depending on the user's selection (i.e., the value of the choice variable).

Program to Create a Menu Driven Software in C Using Function

To improve the readability and manageability of our source code, we can also use functions to implement the menu-driven program in C. Let's look at an example to understand the concept of functions in menu-driven programs:

Code:

Output:

Explanation

In the above example, we first created two methods, namely odd_even() and prime(). Here, the odd_even() method is used to check whether the input number is odd or even, whereas the prime() method is used to verify whether the input number is prime or not. These two functions are executed based on the choice entered by the user. We initialized a choice variable to take the choice from the user. This variable is then passed as an expression to the switch statement. Depending on the value of the choice variable, a case block is executed i.e., if the value of choice is 1 then the odd_even() method is executed, if 2 then the prime() method is executed, and the value 3 is used to exit from the menu, and any other value is considered invalid.

Because of the use of separate functions inside each case block, we can easily modify these functions without affecting the whole code. Hence, this approach helps us to separate the user’s menu from the actual functionality and allows us to write a clean, manageable, and readable menu-driven program in C.